Which chemicals drive biological effects in wastewater and recycled water?

Abstract

Removal of organic micropollutants from wastewater during secondary treatment followed by reverse osmosis and UV disinfection was evaluated by a combination of four in-vitro cell-based bioassays and chemical analysis of 299 organic compounds. Concentrations detected in recycled water were below the Australian Guidelines for Water Recycling. Thus the detected chemicals were considered not to pose any health risk. The detected pesticides in the wastewater treatment plant effluent and partially advanced treated water explained all observed effects on photosynthesis inhibition. In contrast, mixture toxicity experiments with designed mixtures containing all detected chemicals at their measured concentrations demonstrated that the known chemicals explained less than 3% of the observed cytotoxicity and less than 1% of the oxidative stress response. Pesticides followed by pharmaceuticals and personal care products dominated the observed mixture effects. The detected chemicals were not related to the observed genotoxicity. The large proportion of unknown toxicity calls for effect monitoring complementary to chemical monitoring.

Assessing the ecological long-term impact of wastewater irrigation on soil and water based on bioassays and chemical analyses

“…Consequently, the presence of phytotoxic contaminants in the WW feed and their partial removal by soil passage appears to be the most likely explanation for the observed patterns. This is in agreement with Tang et al (2014) who identified organic micropollutants present in treated municipal wastewater as the cause for growth inhibition of primary producers. Deterioration of water quality by passage through some of the soils was only indicated by P. subcapitata and will be discussed later on.…”

“…A theoretical approach to rank the detected substances according to their toxic potential and predict their combined effects is the calculation of the sum of toxic units (sum TUs) based on the measured concentration and toxicity of individual pollutants (Orias and Perrodin, 2013;Verlicchi and Zambello, 2014;Leusch et al, 2014;Tang et al, 2014). In the present study, for only 19 of the detected organic substances toxicity estimates (as EC 50 , the median effective concentration) for Daphnia and green algae could be retrieved from literature to calculate TUs (Tables S.8 and S.9).…”

“…Among these substances, the antibiotics clarithromycin and erythromycin and the herbicides (also used as biocides) diuron, atrazine and terbutryn contributed most to the algal sum TUs. The environmental relevance of these herbicides has been pointed out before as their removal in WWT is poor (K€ ockSchulmeyera et al 2013) and they often dominate negative effects on algae in WW effluents (Tang et al 2014). The antibiotics clarithromycin, erythromycin and sulfamethoxazole have previously been reported to potentially pose a risk to aquatic organisms in treated wastewater, also after its subsequent passage through Table 2 Concentrations of major contaminants in the four soils (s1, s2, s3, s4) after percolation with treated wastewater (WW) and untreated (CON) together with regulatory thresholds (VW) and limit of quantification (LOQ), in mg/kg soil dry weight.…”

Interlaboratory comparison of in vitro bioassays for screening of endocrine active chemicals in recycled water

“…The discrepancy between GR-BEQ and CEQ estimated for hydrocortisone and prednisolone was even greater, accounting for less than 1% of measured GR-BEQs (Table 4). Previous studies have shown good agreement between bioanalytical equivalent concentrations and the levels of natural and synthetic hormones present in water samples (Leusch et al, 2010;Tang et al, 2014). In the present study, relating the measured biological activity to individual chemicals was made difficult for two reasons: few chemicals were monitored by targeted chemical analyses (four GR agonists and two PR agonists, Table SI-4), and there were relatively high analytical method reporting limits (MRLs) for some of the potent estrogens.…”

Depth profile of persistent and emerging organic pollutants upstream of the Three Gorges Dam gathered in 2012/2013

“…They generated artificial mixtures of the detected wide range of micropollutants and concluded that the majority of specific receptor-mediated effects could be attributed to known chemicals. In contrast, only less than 1 % of cytotoxicity and oxidative stress response could be explained by the 269 quantified micropollutants (Tang et al 2014;Tang et al 2013). These results give an outlook in terms of upcoming analytical challenges and in evaluation of mixture toxicity which is neglected by regulatory limits for single compounds.…”